The invention relates to imaging systems, and in particular relates to systems in which images are recorded for electronic processing.
Conventional imaging systems in which images are recorded for electronic processing typically involve the use an array of discrete elements for recording portions of the image, such as a charge coupled device (CCD) array, or a CMOS phototransistor array. For example, as shown in FIG. 1, a conventional imaging system 10 may include an array 12 of image recording elements 14, each of which receives a portion 16 of an image. Devices incorporating such arrays are used for a variety of purposes, including cameras, scanners, monitoring equipment, and robotic vision systems etc.
The resolution of the recorded image depends on the number and size of elements in the array. Although high resolution imaging systems are preferred for certain applications requiring detailed images, high resolution imaging systems generally require more time and memory to capture, process, and transfer the images, than required by lower resolution imaging systems.
Many images contain a significant amount of detail in some areas, but much less detail in other areas. For example, an image may include a human face in the foreground and a statue and sky in the background. The human face may include a relatively large amount of detail, the statue less, and the sky may include the least amount of detail. Certain processing systems, such as file transfer systems, identify the areas of less detail, and compress the data required to represent the image by identifying large contiguous groups of picture elements that are the same as one another. For example, if a portion of an image includes a large number of picture elements that are repetitious, e.g., blue sky, then a single value is identified as applying to the appropriate number of picture elements, instead of representing each of the identical picture elements with separate but equal values.
While such compression algorithms may facilitate certain processing steps such as file transfers, there remains a need to originally capture an image in a more efficient fashion. In particular, there is a need for an imaging system that may selectively obtain high and low resolution data from the same image.